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(#) `File.setReadable()` used to make file world-readable

!!! WARNING: `File.setReadable()` used to make file world-readable
   This is a warning.

Id
:   `SetWorldReadable`
Summary
:   `File.setReadable()` used to make file world-readable
Severity
:   Warning
Category
:   Security
Platform
:   Android
Vendor
:   Android Open Source Project
Feedback
:   https://issuetracker.google.com/issues/new?component=192708
Since
:   1.5.0 (November 2015)
Affects
:   Kotlin and Java files
Editing
:   This check runs on the fly in the IDE editor
See
:   https://goo.gle/SetWorldReadable
Implementation
:   [Source Code](https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:lint/libs/lint-checks/src/main/java/com/android/tools/lint/checks/SecurityDetector.java)
Tests
:   [Source Code](https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:lint/libs/lint-tests/src/test/java/com/android/tools/lint/checks/SecurityDetectorTest.java)

Setting files world-readable is very dangerous, and likely to cause
security holes in applications. It is strongly discouraged; instead,
applications should use more formal mechanisms for interactions such as
`ContentProvider`, `BroadcastReceiver`, and `Service`.

(##) Example

Here is an example of lint warnings produced by this check:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~text
src/test/pkg/WorldWriteableFile.java:41:Warning: Setting file
permissions to world-readable can be risky, review carefully
[SetWorldReadable]
    mFile.setReadable(true, false);
    ------------------------------
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Here is the source file referenced above:

`src/test/pkg/WorldWriteableFile.java`:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~java linenumbers
package test.pkg;

import java.io.File;
import java.io.IOException;
import java.io.OutputStream;
import java.io.InputStream;
import java.io.FileNotFoundException;
import android.content.Context;
import android.content.SharedPreferences;
import android.app.Activity;
import android.os.Bundle;

public class WorldWriteableFile extends Activity {
    File mFile;
    Context mContext;

    public void foo() {
        OutputStream out = null;
        SharedPreferences prefs = null;
        File dir = null;

        boolean success = false;
        try {
            //out = openFileOutput(mFile.getName()); // ok
            out = openFileOutput(mFile.getName(), MODE_PRIVATE); // ok
            out = openFileOutput(mFile.getName(), MODE_WORLD_WRITEABLE);
            out = openFileOutput(mFile.getName(), MODE_WORLD_READABLE);

            prefs = getSharedPreferences(mFile.getName(), 0); // ok
            prefs = getSharedPreferences(mFile.getName(), MODE_PRIVATE); // ok
            prefs = getSharedPreferences(mFile.getName(), MODE_WORLD_WRITEABLE);
            prefs = getSharedPreferences(mFile.getName(), MODE_WORLD_READABLE);

            dir = getDir(mFile.getName(), MODE_PRIVATE); // ok
            dir = getDir(mFile.getName(), MODE_WORLD_WRITEABLE);
            dir = getDir(mFile.getName(), MODE_WORLD_READABLE);

            mFile.setReadable(true, true); // ok
            mFile.setReadable(false, true); // ok
            mFile.setReadable(false, false); // ok
            mFile.setReadable(true, false);
            mFile.setReadable(true); // ok
            mFile.setReadable(false); // ok

            mFile.setWritable(true, true); // ok
            mFile.setWritable(false, true); // ok
            mFile.setWritable(false, false); // ok
            mFile.setWritable(true, false);
            mFile.setWritable(true); // ok
            mFile.setWritable(false); // ok

            // Flickr.get().downloadPhoto(params[0], Flickr.PhotoSize.LARGE,
            // out);
            success = true;
        } catch (FileNotFoundException e) {
        }
    }
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

You can also visit the
[source code](https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:lint/libs/lint-tests/src/test/java/com/android/tools/lint/checks/SecurityDetectorTest.java)
for the unit tests for this check to see additional scenarios.

The above example was automatically extracted from the first unit test
found for this lint check, `SecurityDetector.testWorldWriteable`.
To report a problem with this extracted sample, visit
https://issuetracker.google.com/issues/new?component=192708.

(##) Suppressing

You can suppress false positives using one of the following mechanisms:

* Using a suppression annotation like this on the enclosing
  element:

  ```kt
  // Kotlin
  @Suppress("SetWorldReadable")
  fun method() {
     openFileOutput(...)
  }
  ```

  or

  ```java
  // Java
  @SuppressWarnings("SetWorldReadable")
  void method() {
     openFileOutput(...);
  }
  ```

* Using a suppression comment like this on the line above:

  ```kt
  //noinspection SetWorldReadable
  problematicStatement()
  ```

* Using a special `lint.xml` file in the source tree which turns off
  the check in that folder and any sub folder. A simple file might look
  like this:
  ```xml
  &lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;lint&gt;
      &lt;issue id="SetWorldReadable" severity="ignore" /&gt;
  &lt;/lint&gt;
  ```
  Instead of `ignore` you can also change the severity here, for
  example from `error` to `warning`. You can find additional
  documentation on how to filter issues by path, regular expression and
  so on
  [here](https://googlesamples.github.io/android-custom-lint-rules/usage/lintxml.md.html).

* In Gradle projects, using the DSL syntax to configure lint. For
  example, you can use something like
  ```gradle
  lintOptions {
      disable 'SetWorldReadable'
  }
  ```
  In Android projects this should be nested inside an `android { }`
  block.

* For manual invocations of `lint`, using the `--ignore` flag:
  ```
  $ lint --ignore SetWorldReadable ...`
  ```

* Last, but not least, using baselines, as discussed
  [here](https://googlesamples.github.io/android-custom-lint-rules/usage/baselines.md.html).

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